C#

public class Parent
    {
        public delegate void MyDelegate(string str);
        public static event MyDelegate MYEvent;

        public void Myunc()
        {
            //trigger the event here
            if (MYEvent != null)
            {
                MYEvent("hello listeners");
            }
        }
    }
<pre>

// called when event is triggered<br />
public void Parent_MYEvent(object sender, EventArgs e)<br />
{ <br />
        <br />
}

// called when event is triggered<br />
public void Parent_MYEvent(string info)<br />
{ <br />
        <br />
}

<br />
<br />
public class Parent : TreeView<br />
    {<br />
        public delegate void MyDelegate(string str);<br />
        public static event MyDelegate MYEvent;<br />
<br />
         protected override void OnBeforeExpand(TreeViewCancelEventArgse)<br />
        {<br />
            //trigger the event here<br />
            if (MYEvent != null)  //HOw can we assign value to MYEvent becouse it is allways empty<br />
            {<br />
                Parent.MYEvent("hello listeners"); //Null refrence exception occure<br />
            }<br />
        }<br />
    }<br />
<br />
<br />
    public class MainClass<br />
    {<br />
        public MainClass()<br />
        {<br />
            //subscribe to the event from Parent Class<br />
            Parent.MYEvent += new Parent.MyDelegate(Parent_MYEvent);<br />
        }<br />
<br />
        // called when event is triggered<br />
        public void Parent_MYEvent(string str)<br />
        { <br />
        	MessageBox(str);<br />
        }<br />
    }<br />
<br />

public MainClass()
{
//subscribe to the event from Parent Class
Parent.MYEvent += new Parent.MyDelegate(Parent_MYEvent);
}

public static void Main()
{
    new Thread(TestMethod).Start();
}

static void TestMethod()
{
    int i=0;
    double result;

    try { result = 100/i; }
    catch (DivideByZeroException exc)
    { Console.Write(exc.Message); }
}